JPS63177456A - Semiconductor device - Google Patents

Abstract

PURPOSE:To obtain a semiconductor device where the area occupied by a resistor is made small and whose integration density is enhanced by a method wherein the resistor which is composed of polycrystalline silicon containing impurities is formed inside a groove. CONSTITUTION:The following are provided: a high-concentration buried layer 2, of an opposite conductivity type, formed on a semiconductor substrate 1 of one conductivity type; an epitaxial layer 3, of the opposite conductivity type, formed on the buried layer 2; one pair of grooves 4A, 4B formed in such a way that they reach the buried layer 2 from the surface of the epitaxial layer 3; insulating films 5 formed on the side walls of the grooves; polycrystalline silicon layers 6, of the opposite conductivity type, filled into the grooves 4A, 4B via the insulating films 5. For example, an n<+> type buried layer 2 is formed selectively in a p-type semiconductor substrate 1; an n-type epitaxial layer 3 is formed on the whole surface so as to cover this layer; two grooves 4A, 4B reaching the n<+> type buried layer 2 from the surface of the epitaxial layer are made. Oxide films 5 are formed on the side walls of the grooves 4A, 4B; n-type polycrystalline silicon 6 which is doped with impurities is filled into the grooves 4A, 4B.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a semiconductor device, and particularly to the structure of a semiconductor device having a resistor.

[Conventional technology]

Conventionally, a semiconductor device having a resistance has a resistance layer 12 and an electrode in a resistance region separated by an insulating separation film 10 of an n-type epitaxial layer 3 formed on a P-type semiconductor substrate 1, as shown in FIG. It was common to form a resistor consisting of 7. In FIG. 2, numeral 11 represents an anti-inversion layer.

[Problem that the invention seeks to solve]

In the conventional semiconductor device having the above-mentioned resistor, the surface of the semiconductor substrate is used horizontally to form the resistor, and therefore a large area is required for the resistor region or the region for resistor isolation. For this reason, there has been a drawback that it becomes an obstacle to miniaturization and high integration of semiconductor devices.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above drawbacks, reduce the area occupied by the resistor, and provide a semiconductor device with an improved degree of integration.

[Means for solving problems]

The semiconductor device of the present invention includes a highly concentrated buried layer of opposite conductivity type formed on a semiconductor substrate of − conductivity type, an epitaxial layer of opposite conductivity type formed on the buried layer, and a pair of grooves formed reaching the buried layer;
The semiconductor device includes an insulating film formed on the side surface of a groove, and a reverse conductivity type polycrystalline silicon layer filled inside the groove with the insulating film interposed therebetween.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view of an embodiment of the present invention.

In FIG. 1, there is a layer resistance of 15Ω on the P-type semiconductor substrate 1.
An n + -type buried layer 2 with a / opening is selectively formed, and an n-type epitaxial layer 3 with a thickness of 5 μm is formed on the entire surface so as to cover this. Two grooves 4A and 4B are formed from the surface of the n-type epitaxial layer 3 to the n+-type buried layer 2, each having a depth of about 5 μm and a width of about 2 μm. And the thickness is 0.2 only on the sides of these two grooves 4A and 4B.
An oxide film 5 is formed by thermal oxidation with a thickness of μm, and no oxide film is formed on the bottom surface of the trench. The insides of these two grooves 4A and 4B are filled with n-type polycrystalline silicon 6 doped with an impurity of resistivity 2 and Ωμm, and this impurity-doped n-type polycrystalline silicon 6 is n It is electrically connected to the mold embedding layer 2. Note that 7A and 7B are electrodes electrically connected to this n-type polycrystalline silicon 6.

In this embodiment configured in this way, the electrodes 7A,
A resistor is formed through the n-type polycrystalline silicon 6 and the n+ type buried layer 2 between 7B.

For example, if the distance between the grooves 4A and 4B is 10 μm, the n+ type buried layer is 5 μm x 10 μm, and the open pattern of the groove is 2 μm x 2 μm, the resistance value of one groove is 2Ωμm x 5 μm/( 2μm×2μm)=2
．． It becomes 5 kΩ, and the two grooves make it 5 Ω. On the other hand, n
The resistance value due to the + type buried layer is 16Ω/lo x 10μrn15
μm=32Ω, and the resistance value of the buried layer can be ignored compared to the resistance of the groove, and a resistor having a desired resistance value can be obtained by changing the size of the groove.

〔Effect of the invention〕

As explained above, the present invention has the effect of forming a resistor with a small area by forming a resistor made of polycrystalline silicon containing impurities in the groove, and therefore the degree of integration of a semiconductor device is improved. .

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an embodiment of the present invention, and FIG. 2 is a sectional view of an example of a conventional semiconductor device. DESCRIPTION OF SYMBOLS 1...P-type semiconductor substrate, 2...n+ type buried layer, 3...
...N-type epitaxial layer, 4A, 4B...groove, 5.
...Oxide film, 6...N-type polycrystalline silicon, 7A, 7
B...electrode, 10...insulating separation film, 11...-inversion prevention layer, 12...low resistance layer.

Claims (1)

[Claims] A highly concentrated buried layer of opposite conductivity type formed on a semiconductor substrate of one conductivity type, an epitaxial layer of opposite conductivity type formed on the buried layer, and a layer formed by reaching the buried layer from the surface of the epitaxial layer. A semiconductor device comprising: a pair of grooves formed on the substrate; an insulating film formed on the side surfaces of the groove; and an opposite conductivity type polycrystalline silicon layer filled inside the groove with the insulating film interposed therebetween. .